The present invention relates generally to electrical cables and leads and more particularly to a flexible electrical cable.
Such a cable has two stranded conductors, two cable fillers and one rubber sheathing. These types of cable leads are used to supply current to two-pole, mobile device that consumes electricity such as the magnet of a lifting-magnet-type crane.
A two-conductor electrical cable used to supply current to a mobile device, such as a tool or a movable machine part, is disclosed in U.S. Pat. No. 2,900,437. This known cable has good flexibility, a high resistance to stress resulting from impacts, good tensile strength and resistance to strain caused by bending. The cable is constructed from two conductors which are stranded together. Each conductor includes a high-tensile fibrous core, fine copper wires wound onto this core, a braided covering of textile fibers, and a two-layer insulation of rubber. The two stranded conductors may be surrounded by an inner sheathing, which also fills in the interstices between the strands of the conductors. Alternatively, the interstices are filled with a fibrous filling material. Above this layer is a braided covering of textile fibers and an outer sheathing of rubber.
Another known two-conductor flexible cable for supplying current to portable devices is disclosed in U.S. Pat. No. 2,186,793. In this known conductor the interstices are filled with a cable filler made of rubber or textile fibers. Alternatively, the interstices are filled with a rubber strand which expands, producing an insulating foam when the cable is vulcanized. The conductors have only one lead and one rubber insulation layer, and the cable has a simple rubber sheathing.
Additionally, in German Printed Patent 20 39 870, the interstices in a two-conductor cable are filled with sectional elements. The boundary of the sectional elements in the plane of the cable cross-section form circular segments. These circular segments are adapted to fit the contour of the two stranded conductors and the inner contour of the inner sheathing. In this case, the cable fillers are manufactured as one piece with the conductor insulation.
The problem with the prior art is that it does not provide a flexible electrical cable that is simple to construct, that is tension-proof and capable of withstanding impacts and high dynamic stresses such as occur in cables supplying current to the magnet of a lifting-magnet-type crane.